The accelerator installation TESLA in Vinca will produce protons of energies up to 30 MeV on the first, and up to 70 MeV on the second channel. On both channels, advanced experiments need numerical simulation of protons passage through different materials. The accelerator target geometry is usually complex, and protons arrive on targets with arbitrary spectrum. It is reasonable to accept that this geometry can be presented with planes and second order surfaces by RFG code and/or by PENGEM modeler from PENELOPE code. Inside this geometry, appear materials of different composes - compounds and mixture of elements. Therefore, numerical simulation of proton flow runs in 3D sources and 3D targets.
Protons energy on second channel, in the beginning of the program development, has determinate limit of protons energy in the range from 100 keV to 100 MeV. But accelerators elsewhere in the world produce protons up to 250 MeV (as at IUCF, Indiana Univiversity, USA and INR RAN, Troitsk, Russia) for various investigation purposes and for tumor therapy. Because of need for wide international cooperation, it was necessary that upper limit of protons energy should be 250 MeV.
In proton experiments planing , it is understandable that proton beam is determinate by the shape of a channel, and that targets in beam are space adjustable according to experiment conditions. For numerical experiments, it is reasonable to accept fixed target, and that proton beam should be within space angle of 4p, according to symmetrical axis of a target.
Monte Carlo techniques make possible to record all protons stages, but usually only some of them are of interest. Space distribution of absorbed energy and absorbed energy per target zones are representative groups. That is why the greatest attention has been given to that kind of output data. In most experiments, beam has to be modified by the targets of complex form and contents. Adjustment of protons beam for experiment needs knowledge of space, energy and angular distribution - spectrum on the target. Therefore, it is necessary to record those distributions as well, and to present them graphically to the researcher.
All versions of SRNA codes run on common PC computers. Since FORTRAN 77 is dominant, it is understandable that the program was written in that language. This approach was also influenced by the author's experience in developing FOTELP software - Monte Carlo Simulation of Photons, Electrons and Positrons Transport. Transition on other computers and compilers is possible with minor changes in program (clock, date).
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